1. Field of the Invention
The present invention relates to a carrier tape on which a number of semiconductor chips are bonded in a process of manufacturing semiconductor devices and to a method for resin-molding semiconductor chips using the carrier tape.
2. Description of the Related Art
A tape automated bonding (T. A. B.) method, which uses a tape carrier, has recently been adopted for bonding electrodes of semiconductor integrated circuits in place of the wire bonding method.
FIGS. 4A and 4B illustrate a conventional carrier tape, on which a semiconductor chip 3 is mounted, used in the T. A. B. method. The carrier tape has a flexible film 1 made of an insulating material such as plastic, e.g., polyimide resin, and leads 7 made of a conductive material such as copper. The film 1 has perforations 2 regularly disposed at equal intervals along its opposite sides, a rectangular opening 4 formed at its center and called a center device hole, and outer lead holes 6 formed around the periphery of the opening 4. The leads 7 are supported by a support portion 9 defined between the opening 4 and the outer lead holes 6. The tips of the leads 7 extend into the opening 4 and serve as inner leads 7a. Central portions of the leads 7 are positioned above the outer lead holes 6 and serve as outer leads 7b. The rear ends of the leads 7 are formed as test pads 7c. A semiconductor chip 3 is connected to the inner leads 7a of the leads 7 through the medium of bumps 8 (FIG. 4B).
In such a carrier tape, bridging portions 5 are formed between adjacent outer lead holes 6 to secure the support portions 9 to the outer or remaining portion of the film 1 whereby the inner leads 7a are supported on the support portions 9 to be positioned in place with high accuracy.
A conventional process of manufacturing this type of semiconductor device will be described below.
As shown in FIGS. 5A and 5B, the semiconductor chip 3 is first introduced into the opening 4 of the film 1, and the bumps 8 provided on electrodes of the semiconductor chip 3 are connected to the inner leads 7a in a thermocompression bonding method. Subsequently, resin-molding of the semiconductor chip 3 is carried out to provide a resin-molded semiconductor device.
Generally, such a semiconductor chip 3 is resin-molded by the following methods.
In a first method called a potting molding method, as shown in FIGS. 6A and 6B, a liquid resin 14 is forced to flow out of the tip of a nozzle 13 to cover the semiconductor chip 3 which is mounted on a carrier tape and the area adjacent the chip. Since this method utilizes no mold, however, it is impossible to make the shape and size of the thus formed resin package uniform. Furthermore, since the liquid resin 14 is used, this method has the disadvantage that the moisture included in the resin 14 may adversely affect the semiconductor chip 3.
FIGS. 7A to 7D show a second method for resin-molding a semiconductor chip 3. After leads 7 are cut at certain portions thereof between their outer leads 7b and test pads 7c and a film 1 is cut at bridging portions 5 thereof, the outer leads 7b are connected to a lead frame 15 as shown in FIGS. 7A and 7B. The semiconductor chip 3 is then accommodated in a cavity 12 formed between a pair of mold halves 10 and 11 as shown in FIG. 7C. Subsequently, a resin 14 is introduced into the cavity 12 through a gate 16 defined between the upper mold half 10 and the lead frame 15 by a low pressure transfer molding method, whereby a resin-molded semiconductor device is produced as shown in FIG. 7D. Since the semiconductor chip 3 is, however, resin-molded together with a part of the lead frame 15 in the second method, the thickness of the resin package becomes undesirably large.
A third method for resin-molding a semiconductor chip 3 is illustrated in FIGS. 8A to 8C.
In this third method, a carrier tape, such as shown in FIG. 8A, is directly held between a pair of upper and lower mold halves 10 and 11, and a semiconductor chip 3 is accommodated in a cavity 12 in the lower mold half 11 as shown in FIG. 8B. A resin 14 in the form of an epoxy resin is then injected into the cavity 12 through a gate 16 defined above one 6a of the outer lead holes 6 by means of a low pressure transfer molding method, whereby a resin-molded semiconductor device is produced as shown in FIG. 8C.
In this case, however, the resin 14 is introduced into the cavity 12 through the outer lead hole 6a along an arrow A shown in FIG. 8A. That is, the resin 14 is supplied to not only the cavity 12 but also the outer lead hole 6a of the film 1 so that resin burrs 14a are formed in the outer lead hole 6a as shown in FIG. 8C. For this reason, it is necessary to remove the resin burrs 14a after resin-molding the semiconductor chip 3. As a result, the process of manufacturing semiconductor devices becomes complicated. In addition, the thin outer leads 7b, which have a thickness of about 35 .mu.m, are easily damaged when the resin burrs 14a are removed, thereby reducing the reliability of the semiconductor devices.